Hi HN! here's a tool I just deployed that renders PDFs in dark mode without destroying the images. Internal and external links stay intact, and I decided to implement export since I'm not a fan of platform lock-in: you can view your dark PDF in your preferred reader, on any device. It's a side project born from a personal need first and foremost. When I was reading in the factory the books that eventually helped me get out of it, I had the problem that many study materials and books contained images and charts that forced me, with the dark readers available at the time, to always keep the original file in multitasking since the images became, to put it mildly, strange. I hope it can help some of you who have this same need. I think it could be very useful for researchers, but only future adoption will tell.With that premise, I'd like to share the choices that made all of this possible. To do so, I'll walk through the three layers that veil creates from the original PDF:- Layer 1: CSS filter. I use invert(0.86) hue rotate(180deg) on the main canvas. I use 0.86 instead of 1.0 because I found that full inversion produces a pure black and pure white that are too aggressive for prolonged reading. 0.86 yields a soft dark grey (around #242424, though it depends on the document's white) and a muted white (around #DBDBDB) for the text, which I found to be the most comfortable value for hours of reading.- Layer 2: image protection. A second canvas is positioned on top of the first, this time with no filters. Through PDF.js's public API getOperatorList(), I walk the PDF's operator list and reconstruct the CTM stack, that is the save, restore and transform operations the PDF uses to position every object on the page. When I encounter a paintImageXObject (opcode 85 in PDF.js v5), the current transformation matrix gives me the exact bounds of the image. At that point I copy those pixels from a clean render onto the overlay. I didn't f
FL score
out of 100
Verdict
high confidence
Competition
8
competitors found, emerging market, funded players
Trend
No signal yet
A browser-based tool for dark mode PDFs that preserves images, targeting frustrated readers and researchers.
The pain
The gap
Build angle
Strengths
Questions about this idea?
FlyBot reads the scoring and gives you a second opinion on “Veil – Dark mode PDFs without destroying images, runs in the browser”.
Risks
Next steps
Fly Labs Method
Is the pain real, is there a gap, is it the right time, can one person build it.
A highly specific problem for dark mode PDF users (distorted images) that is real and painful, with a clear solution gap. Willingness to pay exists, but the technical complexity for a solo builder and strong incumbents in the broader market are notable risks.
Value Equation
Dream outcome and how likely it feels, against the time and effort it costs.
Strong value proposition and market need, but faces significant build complexity and a crowded broader market.
One-Person Business
Curiosity pull, identity fit, and a path from free value to paid for a solo creator.
Strong problem clarity and creator fit for a complex niche, but faces challenges in simplicity, monetization, and market leverage.
Viral Frameworks
Hook strength, shareability, and how cheaply it can be tested.
Clear value proposition for a specific audience, but distribution and business model against strong competition are key challenges.
Builder Lens
Evidence the problem exists, timing, defensibility, and a model that fits on a napkin.
Addresses a real, specific pain for a clear user with a viable initial solution, showing promise for future growth.
Why this verdict
Five lenses, one composite. How scoring works
The angle
This weekend
Who is already there, emerging market
A free and open-source browser extension that enables dark mode on all websites, including PDFs, by inverting bright colors to be high contrast and easy to read.
Pricing: Free
A browser extension that applies dark mode to nearly any website and PDFs, utilizing a new approach that aims to improve the browsing experience without simply inverting colors.
Pricing: Free (Lite version with 5-website limit) / Paid (Pro version with 3-month free trial, then subscription)
A free dark mode PDF reader designed for comfortable nighttime reading, offering clean PDF color inversion that preserves image readability and allows local annotation.
Pricing: Free
A web extension for Chrome and Firefox that provides custom color schemes for all websites, including PDFs, offering full color control and community themes.
Pricing: Free and Open Source
A free PDF viewer and editor with a dark mode, also notable for its AI-powered Copilot feature.
Pricing: Free
A comprehensive PDF reader and editor that includes a one-click dark mode feature and an AI assistant.
Pricing: Free version with limited features; $16/month; $96.75 one-time purchase.
A leading PDF solution offering various features, including the ability to view PDFs in dark mode by adjusting the PDF background or interface color.
Pricing: High fee for advanced features; subscription-based.
A full-featured alternative to Adobe Acrobat that includes dark mode options for document viewing, alongside annotation, form filling, and editing tools.
Pricing: Not explicitly stated, but often offers a free reader with paid upgrades for advanced features.
What they charge
Recent news
Hacker News, March 26, 2026
Zovo, March 13, 2026
Zovo, March 21, 2026
SwifDoo PDF, January 16, 2026
YouTube, January 20, 2026
Market signals
The market for dark mode PDF readers and browser extensions is growing, driven by increasing awareness of eye strain from bright screens and a preference for dark mode across various applications. Recent news and product updates from multiple companies, including those with AI integration, indicate continued investment and development in this space. This suggests a large and expanding market, moving beyond niche, as dark mode becomes a standard expectation for digital content consumption.
What frustrates people
Last summer we faced a conundrum at my company, Tiger Data, a Postgres cloud vendor whose main business is in timeseries data. We were trying to grow our business towards emerging AI-centric workloads and wanted to provide a state-of-the-art hybrid search stack in Postgres. We'd already built pgvectorscale in house with the goal of scaling semantic search beyond pgvector's main memory limitations. We just needed a scalable ranked keyword search solution too.The problem: core Postgres doesn't provide this; the leading Postgres BM25 extension, ParadeDB, is guarded behind AGPL; developing our own extension appeared daunting. We'd need a small team of sharp engineers and 6-12 months, I figured. And we'd probably still fall short of the performance of a mature system like Parade/Tantivy.Or would we? I'd be experimenting long enough with AI-boosted development at that point to realize that with the latest tools (Claude Code + Opus) and an experienced hand (I've been working in database systems internals for 25 years now), the old time estimates pretty much go out the window.I told our CTO I thought I could solo the project in one quarter. This raised some eyebrows.It did take a little more time than that (two quarters), and we got some real help from the community (amazing!) after open-sourcing the pre-release. But I'm thrilled/exhausted today to share that pg_textsearch v1.0 is freely available via open source (Postgres license), on Tiger Data cloud, and hopefully soon, a hyperscalar near you:https://github.com/timescale/pg_textsearchIn the blog post accompanying the release, I overview the architecture and present benchmark results using MS-MARCO. To my surprise, we were not only able to meet Parade/Tantivy's query performance, but exceed it substantially, measuring a 4.7x advantage on query throughput at scale:https://www.tigerdata.com/blog/pg-textsearch-bm25-fu
AI
Hi HN!I recently switched from a Fedora/GNOME laptop to a MacBook Air. My old setup served me well as a portable workstation, but I’ve started traveling more while working remotely and needed something with similar performance but better battery life. The main thing I missed was a simple taskbar that shows the windows in the current workspace instead of a Dock that mixes everything together.I built boringBar so I would not have to use the Dock. It shows only the windows in the current Space, lets you switch Spaces by scrolling on the bar, and adds a desktop switcher so you can jump directly to any Space. You can also hide the system Dock, pin apps, preview windows with thumbnails, and launch apps from a searchable menu (I keep Spotlight disabled because for some reason it uses a lot of system resources on my machine).I’ve been dogfooding it for a few months now, and it finally felt polished enough to share.It’s for people who like macOS but want window management to feel a bit more like GNOME, Windows, or a traditional taskbar. It’s also for people like me who wanted an easier transition to macOS, especially now that Windows feels increasingly user-hostile.I’d love feedback on the UX, bugs, and whether this solves the same Dock/Spaces pain for anyone else.P.S. It might also appeal to people who feel nostalgic for the GNOME 2 desktop of yore. I started my Linux journey with it, and boringBar brings back some of that feeling for me.
AI
### Describe the project you are working on Godot C# bindings ### Describe the problem or limitation you are having in your project For the past weeks, I've been discussing with several Unity users intending to move to Godot C# regarding dealing with the C# garbage collector. The most common complaint I hear from users is that, in Unity, allocations can trigger unexpected GC spikes into the game. In Godot, we target to make all of the high performance APIs (those that intended to be called every frame) not allocate any memory, so theoretically the GC should not be a problem. Additionally, Godot starting from 4.0, uses the Microsoft CoreCLR version of .net, which also supposedly has a better garbage collector than Unity. But in all, after several discussions with Unity users, neither is enough reassurance for them, and they would really feel safer if Godot exposed a zero allocation API. ### Describe the feature / enhancement and how it helps to overcome the problem or limitation The idea of this proposal is that Godot exposes zero allocation versions of many functions in the C# API, that users can use if they desire. Technically, this could be done from the binding generator itself, without breaking compatibility, and without doing any modification to Godot itself. ### Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams **WARNING** I am not familiar with C#, so take this as pseudocode. Imagine you have two functions exposed as to C#: ```C# void MyClass.SetArray( Vector2[] array); Vector2[] MyClass.GetArray(); ``` This works and is pretty and intuitive. However, it has two problems: * GC is allocated on return * Memory is copied to Godot native formats every time there is a call. The idea is to add NoAlloc versions, which can be generated directly by the binder automatically when required: ```C# void MyClass.SetArrayNoAlloc( Godot.Collections.PackedVector2Array array); void MyCl
AI